Determination of Trans-resveratrol in Wines, Spirits, and Grape Juices Using Solid-Phase Micro Extraction Coupled to Liquid Chromatography with UV Diode-Array Detection

Solid phase microextraction (polyacrylate fiber), coupled to liquid chromatography with UV diode-array detection, has been optimized for the determination of trans-resveratrol in wines, spirits, and grape juices. The main aspects influencing fiber adsorption (fiber coating, extraction time, ethanol content, salt addition) and desorption (desorption and injection time, desorption solvent mixture composition, carryover) of the analyte have been investigated. The method permitted a fast and simple determination of free trans-resveratrol in commercial samples. It was found in all the analyzed samples at concentration levels ranging from 0.007 to 4.486 μg mL−1. Total trans-resveratrol concentrations were also evaluated after enzymatic deconjugation of piceid.